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United States Patent |
5,055,261
|
Khoja
,   et al.
|
October 8, 1991
|
Reagent test strip reading instrument
Abstract
A multiple reagent test strip-reading instrument having rails extending
from a loading area to one or more reading station platforms and then to a
waste receptacle, a reciprocating blotter arm which contacts individual
reagent strips sequentially placed transversely on the rails in the
loading area, moving individual strips along the rails to an indexing
strip advancing mechanism which intermittently advances the strips along
the rails in spaced parallel relation, and after each advance, allows the
strips to dwell for a predetermined time period; individual test strips
being thereby sequentially delivered to reading position on the reading
station platform where, during the dwell period, they are read by
reflectance photometry. After reading, the strips are moved to the waste
receptacle. Means is provided for insuring that each test strip is
delivered to reading position in registration with the read head of the
photometer, and means is also provided for pressing each test strip flat
against the reading station platform. The indexing mechanism employs a
strip advancing member provided with parallel rows of equally spaced
upstanding pegs or fingers, there being guiding and drive means for
imparting movement to said member along a vertical orbital path having a
generally circular extent and also having a rectilinear extent parallel
with the rails, said pegs intersecting the plane of the reagent strips on
the rails when said member moves forwardly along said rectilinear extent
and being withdrawn from said plane when said member moves rearwardly
along said circular extent.
Inventors:
|
Khoja; Mirza A. (Elkhart, IN);
Wogoman; Frank W. (South Bend, IN)
|
Assignee:
|
Miles Inc. (Elkhart, IN)
|
Appl. No.:
|
270849 |
Filed:
|
November 14, 1988 |
Current U.S. Class: |
422/64; 15/102; 422/63; 422/68.1; 422/82.05 |
Intern'l Class: |
G01N 035/02 |
Field of Search: |
422/63,64,68.1,82.05
15/102
198/339.1,740,741
|
References Cited
U.S. Patent Documents
1445899 | Feb., 1923 | McGregor | 198/636.
|
2969866 | Jan., 1961 | Musgrave | 198/456.
|
3578412 | May., 1971 | Martin | 198/741.
|
3645690 | Feb., 1972 | Rochte et al. | 436/48.
|
3730333 | May., 1973 | Wakabayashi et al. | 198/741.
|
4059405 | Nov., 1977 | Sodickson et al. | 436/44.
|
4063817 | Dec., 1977 | Shimamura et al. | 436/34.
|
4269803 | May., 1981 | Jessop | 422/63.
|
4306401 | Dec., 1981 | Stohlquist et al. | 198/740.
|
4458376 | Jul., 1984 | Sitko | 15/102.
|
4539182 | Sep., 1985 | Johnson et al. | 436/44.
|
Primary Examiner: Fisher; Richard V.
Assistant Examiner: Friedman; Charles K.
Attorney, Agent or Firm: Coe; Roger N.
Parent Case Text
RELATED APPLICATIONS
This is a division Ser. No. 32,607 filed Apr. 1, 1987, now U.S. Pat. No.
4,820,491, which is a division of application Ser. No. 649,363, filed
Sept. 11, 1984, now U.S. Pat. No. 4,689,202.
Claims
We claim:
1. In combination, at least two spaced generally parallel and horizontal,
stationary rails extending to a reading station platform where a test
strip is read by reflectance photometry and adapted to support a test
strip disposed transversely thereon; a movable test strip advancing member
in the form of a removably mounted tray having spaced generally vertically
extending pegs, means for guiding movement of said strip advancing member
along an orbital path in a generally vertical plane aligned with said
rails, said orbital path including a rectilinear generally horizontal
advancing extent parallel with said rails wherein said pegs intersect the
plane of a test strip on said rails and are adapted to engage and to
advance such test strip along said rails, said orbital path also having a
generally circular return extent wherein said pegs are withdrawn from said
plane; and drive means for moving said strip advancing member along said
orbital path.
2. The combination of claim 1 which additionally comprises control means
for said drive means effecting disposition of said strip advancing member
along the return extent of its orbital path on normal termination of
operation of the drive means.
3. The combination of claim 2 in which the strip advancing member is
mounted for slidable transverse removable movement on a portion of said
guiding means, and on said normal termination of operation of the drive
means is disposed in a position vertically offset from said rails so that
it can be removed and replaced without interference by said rails.
4. The combination of claim 2 wherein said rails are formed on a base
member mounted for slidable transverse removable movement on a frame.
5. The combination of claim 4 wherein on normal termination of operation of
said drive means said strip advancing member is disposed in a position
offset vertically from said base member in which it permits removal and
replacement of the latter without interference by said strip advancing
member.
6. The combination of claim 2 wherein said strip advancing member is
mounted for slidable transverse removable movement on a portion of said
guiding means, said rails are formed on an apertured base tray mounted for
slidable transverse removable movement on a frame, and on a normal
termination of operation of said drive means, said first-mentioned tray is
disposed in a position vertically offset from said base tray so that
either tray can be removed and replaced without interference by the other.
7. The combination of claim 1 in which the orbital path of said strip
advancing member and the position of the pegs thereon are so related to
said reading station platform that as a test strip moved by the pegs
reaches a reading position on the reading station platform, the strip
advancing member simultaneously reaches the forward end of the horizontal
extent of its orbital path.
8. The combination of claim 7 which additionally comprises control means
for said drive means which temporarily terminates operation of said drive
means for a predetermined dwell period when the strip advancing member
reaches the forward end of the horizontal extent of its orbital path.
9. The combination of claim 8 which additionally comprises means for
reading a test strip in a reading position on the reading station platform
during the dwell period.
10. The combination of claim 9 wherein said strip reading means comprises
multiple optical elements for reflectance photometry reading of the
respective test areas of a multiple test reagent strip in said reading
position.
11. The combination of claim 1 which additionally comprises a blotter
member mounted adjacent and extending transversely across said rails for
reciprocating movement along said rails between retracted and advanced
positions, said blotter member being adapted, during advancing movement
thereof, to remove excess liquid from a test strip while advancing the
latter along said rails from a first to a second position; means for
driving said blotter member in timed relation with movement of said strip
advancing member, so that said blotter member is in its advanced position
when said strip advancing member is about to begin movement along the
horizontal advancing extent of its orbital path with the pegs thereof
positioned behind and adapted to engage a test strip move to its said
second position by movement of said blotter member to its advanced
position, said peg position preventing return movement of said test strip
with said blotter member on return of the latter to its retracted
position.
12. The combination of claim 11 wherein the blotter member is formed with
cut away portions for accommodating the pegs of the strip advancing member
without interference during retractile movement of the blotter member from
its advanced position and simultaneous advancing movement of said strip
advancing member.
13. Reflectance photometry apparatus for moving a driven member which is in
the form of a removably mounted tray having parallel rows of spaced,
upstanding projections from an initial position along a generally planar
orbital path having a generally circular extent and also having a
generally rectilinear extent thereby to advance a test device to a reading
station platform, comprising at least one first shoulder means comprising
two spaced shoulder members having coplanar rectilinear surface; second
shoulder means comprising a pair of spaced rollers respectively cooperable
with said coplanar rectilinear surfaces on said driven member; means for
biasing said driven member in a direction tending to cause engagement of
said rectilinear surface by said second shoulder means; at least one
driving member mounted for rotation on an axis generally normal to the
plane of said orbital path and having a radially offset actuating member;
and third shoulder means comprising a pair of parallel slots formed in the
driven member, extending at an acute angle with respect to said
rectilinear surface, and within which said actuating members are
respectively slidable, said slots having a width generally the same as the
diameter of the cylindrical actuating members therein and having a length
greater than their width, on said driven member engageable by said
actuating member upon rotation of said driving member to cause movement of
said driven member against the bias of said biasing means along a
generally circular path causing movement of said second shoulder means out
of contact with said rectilinear surface at said initial position and
subsequent return thereof into contact with the rectilinear surface at a
second position thereon spaced from said initial position, said third
should means being shaped such that, upon continued rotation of said
driving member, engagement of the actuating member with the third should
means causes rectilinear movement of the second shoulder means along said
rectilinear surface from said second position to said initial position to
thereby complete one cycle of orbital movement of said second shoulder
means and said driven member.
14. Apparatus as in claim 13 wherein there are two spaced, like driving
members having parallel axes of rotation, and each driving member has a
rotatable cylindrical actuating member whose axis of rotation is parallel
with that of the related driving member.
15. Apparatus as in claim 13 which additionally comprises a pair of
generally horizontal spaced parallel, stationary rails adapted to support
thereon a test strip and with which said rectilinear surface is generally
parallel, and wherein said driven member carries spaced pegs which
intersect the plane of the upper surface of said rails during rectilinear
movement of said driven member, said pegs being spaced from said plane
during a portion of the movement of the driven member along the circular
extent of its orbital path.
16. Apparatus as i claim 15 wherein said spaced pegs are upstanding, and
during a portion of the movement of the driven member along the circular
extent of its orbital path said pegs are spaced below the plane of the
upper surface of the rails.
17. Apparatus as in claim 16 wherein said pegs project from a tray which is
removably mounted on the driven member.
18. Apparatus as in claim 16 which comprises a tray which carries spaced
parallel rows of equally spaced upstanding pegs, each of said spaced pegs
being included in one of said rows.
19. In a reflectance photometry reagent test reading instrument having a
reading station platform, the combination of at least two spaced generally
parallel, horizontal, stationary rails adapted to support a test strip
disposed transversely thereon, a blotter member mounted adjacent and
extending transversely across said rails for reciprocating movement along
said rails between retracted and advanced positions, said blotter member
being adapted during advancing movement thereof to contact an edge portion
of a test strip on said rails and to remove excess liquid therefrom, as
well as to advance said test strip along said rails from a first to a
second position; means for driving said blotter member; spaced upstanding
pegs extending from a removably mounted tray, said pegs having a first
position in which they are engageable with a rear edge portion of a test
strip moved to said second position by said blotter member; and means for
moving said pegs to their said first position in timed relation with
movement of said blotter member to its advanced position, said pegs in
their first position preventing movement of a test strip from its second
position with said blotter member on return of the latter toward its
retracted position.
20. The combination of claim 19 wherein said blotter member is formed with
cut away portions for accommodating said pegs without interference upon
retractile movement of the blotter member from its advanced position.
21. The combination of claim 19 which is useful with multiple test strip
having spaced absorbent test areas separated by substantially nonabsorbent
areas, and which additionally comprises means effective during said
advancing movement of a test strip toward its said second position for
causing endwise movement of said test strip as necessary to effect
registration of nonabsorbent areas thereof with said pegs when said strip
reaches its second position.
Description
TECHNICAL FIELD
This invention relates to the field of clinical chemistry and more
particularly to automated instruments capable of sensing and quantitating
the extent of a color change undergone by one or more test areas of a
reagent strip following contact thereof with a liquid specimen, such as a
urine or blood specimen.
BACKGROUND ART
Reagent strips which comprise one or more test areas capable of undergoing
a color change in response to contact with a liquid specimen which may
contain one or more constituents of interest have found wide acceptance,
particularly in the clinical chemistry field, and have become an extremely
useful tool aiding the physician in the diagnosis of disease. In order to
afford precise quantitation of such color changes not possible when color
comparisons are made with the naked eye, instruments employing reflectance
photometry have been developed for reading test strip color changes. Such
instruments determine with consistent accuracy the amount of color change,
and hence the amount of the sample constituents of interest.
The commercially available strip reading instruments represent a clear
advance in the art. However, the speed with which strips can be read
therewith is not sufficient adequately to cope with the large numbers of
specimens handled by clinical laboratories. This is because in the use of
these instruments one strip must be inserted, read and removed from the
instrument before the same series of steps can be performed on the next
succeeding strip. Moreover, with certain instruments the speed of
operation is limited by the requirement for precise placement of the strip
in the instrument.
Automation of clinical laboratory procedures has provided significant
improvement in the speed with which specimens can be processed. However,
the automated instrumentation developed has thus far been limited to
laboratory chemical analysis procedures involving the use of liquid
reagents, and do not lend themselves to the automated reading of test
strips. Representative of such chemical analyzer instruments are those
disclosed in U.S. Pat. Nos. 3,578,412 and 4,269,803.
The '412 patent discloses horizontal rails 10 which are vertically
reciprocable by a first doubleacting air cylinder 28, and horizontal
serrated racks 14 which are horizontally reciprocable by a second
double-acting air cylinder 34. Plastic multiple cavity liquid sample
receptacles 18 are moved by this arrangement past a series of processing
stations where various analytical steps are performed. The receptacles
have downwardly facing cavity portions at each end, and when the rails 10
are lowered, each such cavity portion fits down over a tooth of a rack 14,
necessitating the use of retainer flanges 48 and hold down members 46.
The '803 patent utilizes a ratchet type reciprocable shuttle block 52
having spring loaded fingers 60 for advancing analysis slides 18 along a
track 25 past metering and analysis stations. The weight of the slides
must be great enough or they must be held down positively by means not
shown, to cause the fingers to be tilted downwardly against the bias of
the loading springs (not shown) when the shuttle block undergoes
retractile movement.
DISCLOSURE OF THE INVENTION
The present invention provides a novel instrument for the expeditious and
facile transport, indexing and reading of reagent strips of the type
having multiple test areas, some of which areas may have an incubation
time which is different from that of other test areas thereof. The
instrument has stationary, generally horizontal rails extending from a
loading area to and through one or more reading stations and thence to a
waste receptacle.
Individual reagent strips to be read by the instrument are sequentially
placed transversely on the rails in the loading area, where accuracy of
such placement is not a critical factor, there being means including a
reciprocating blotter arm for removing excess liquid from each successive
strip and for simultaneously orienting the same normal to the rails, as
well as endwise, as it is moved along the rails toward the first reading
station. As the blotter arm reaches the limit of its advancing movement,
an indexing mechanism operating in timed relation with the blotter arm
engages the strip contacted by the blotter arm and continues movement of
said strip to and through the reading stations.
The indexing mechanism advances the strips in spaced parallel relation a
predetermined distance along the rails, and after each incremental
advance, allows each strip to dwell for a predetermined time period in its
new position. Individual test strips are thereby sequentially delivered to
reading position on the first reading station platform where, during the
dwell period, certain test areas thereof are read by reflectance
photometry. After reading at the first reading station, the strips are
advanced progressively to reading position on the second reading station
platform where other test areas thereof are read by reflectance
photometry.
The indexing mechanism employs a strip advancing member in the form of a
removably mounted tray having parallel rows of spaced upstanding pegs or
fingers. The rails are formed on a removably mounted stationary base tray
which is slotted to permit movement therethrough of the upstanding pegs of
the strip advancing member. The trays prevent exposure of the drive and
guide mechanism to any specimen which might inadvertently drip from test
strips, and when specimen is collected thereby, said trays can be readily
removed, washed and replaced.
Strip engaging means is provided at each reading station for pressing each
test strip thereat flat against the reading station platform to thereby
retain the proper spacing between the strip and the read head. Means is
also provided at each reading station for preventing damage to the test
strip engaging means thereat which might otherwise occur on removal of the
base tray. To this end the strip engaging means is retractably mounted,
and interlock means is provided which prevents removal of the base tray
unless the strip engaging means is retracted to a position in which it
cannot be damaged by such removal.
The indexing mechanism employs guiding and drive means for imparting to the
strip advancing member movement along a vertical orbital path having a
generally circular extent and also having a rectilinear extent which is
parallel with the rails. The pegs of the strip advancing member intersect
and project above the plane of reagent strips on the rails when the strip
advancing member moves forwardly along the rectilinear extent of its
orbital path, and said pegs are withdrawn below the rails during return
movement of the strip advancing member along the circular extent of its
orbital path. The drive means for the strip advancing member includes
means for insuring that termination of movement of the strip advancing
member occurs only while the latter is disposed on the circular portion of
its orbital path with the pegs thereof retracted below the base tray. This
insures that, during shut down, the strip advancing member can be readily
removed without interference with the base tray.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevational view of a reagent test strip reading
instrument embodying the invention, parts being broken away and shown in
section.
FIG. 2 is a plan view of the instrument shown in FIG. 1, one of the read
heads being removed to expose the second reading station platform.
FIG. 3 is a view similar to FIG. 2, with the base tray and the strip
advancing member removed to expose the guiding and driving mechanism for
the strip advancing member;
FIG. 4 is a semidiagrammatic perspective view of the drive and guide
mechanism for the strip advancing member and the blotter member
FIG. 5 is a perspective view of the strip advancing member removed from the
instrument;
FIG. 6 is a vertical sectional view taken along the line VI--VI of FIG. 3;
FIG. 7 is a fragmentary bottom plan view illustrating the shuttle block
guiding mechanism;
FIG. 8 is an enlarged partial transverse vertical sectional view taken
along the line VIII--VIII of FIG. 2, part being broken away and shown in
section;
FIG. 9 is a vertical sectional view taken along the line IX--IX of FIG. 8;
and
FIG. 10 is a view similar to FIG. 9 showing the strip hold down members in
raised position.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to FIGS. 1 to 3 of the drawings the preferred embodiment of
the invention comprises a base frame 11 of generally rectangular
configuration which has front and rear wall portions 12 and 13 and end
wall portions 14 and 15. The end wall portions 14 and 15 comprise parallel
horizontal front to rearwardly extending bar portions 16 and 17 which
function as supporting arms for a base tray to be described hereinafter.
Projecting forwardly from the rear wall portion 13 is a pair of spaced
horizontal bar members 18 and 19 which function as supporting arms for
read heads to be described hereinafter.
As best shown in FIGS. 1 and 2, the numeral 20 indicates a fixed base tray
which is formed on its underside near one end with guideway portions 21
and 22 which are cooperable with the tray supporting arm 16, and near the
other end with guideway portions 23 and 24 which are cooperable with the
supporting arm 17. The cooperation of guideways 21 to 24 with arms 16 and
17 is such that the tray 20 can be mounted in operative position by
sliding the guideways thereof telescopically over the arms 16 and 17 as
the tray 20 is moved transversely inwardly, i.e. rearwardly therealong.
Similarly, the tray 20 can be removed from operative position, for example
to be emptied and washed, by sliding transverse outward, i.e. forward,
movement thereof along the bars 16 and 17. Tray 20 has integral
projections (not shown) on its undersurface which are positioned to engage
the front end surfaces of the supporting arms 16 and 17, respectively, to
thereby define the innermost or operative position of said tray on the
frame 11.
The tray 20 has four general areas, i.e. a loading area 25, a first reading
station platform 26, a second reading station platform 27, and a waste
receptacle 28. The tray 20 is formed in the loading area with spaced
parallel generally horizontal rails 29 and 30, the upper surfaces of which
are spaced above the adjacent bottom portions of the tray. Rails 29 and 30
are spaced apart a distance approximating the length of the reagent test
bearing portion of the reagent test strips to be processed through the
instrument. Tray 20 is also formed with an intermediate rail 31 whose
upper surface rises from the level of the bottom of the tray at its left
hand end to the level of rails 29 and 30 at its right hand end. Rails 29
to 31 extend to the reading station platform 26, at which point the upper
surfaces thereof are flush with said platform.
The reading station platforms 26 and 27 are alike, are parallel and have
elongated transversely extending planar rectangular upper surfaces spaced
above the level of the adjacent tray bottom portions. The platforms 26 and
27 are of a length and width to provide a flat surface support for the
full length and width of at least the reagent test bearing portion of a
reagent test strip disposed thereon.
Tray 20 is formed with spaced horizontal rails 32, 33 and 34 which are
generally alined with rails 29, 30, and 31, respectively, and which extend
from the platform 26 to the platform 27. The upper surfaces of rails 32 to
34 are spaced above the adjacent tray bottom portions and are generally
coplanar with the surfaces of the platforms 26 and 27. Tray 20 is also
formed with rails 35, 36 and 37 which extend horizontally from platform 27
to the waste receptacle 28 and are generally aligned with rails 32 to 34
respectively.
The rails thus far described provide generally line contact support for
reagent strips extending thereacross and slidably moved therealong in a
manner to be hereinafter described. The line contact minimizes adhesion
resulting from surface tension of the liquid specimens with which the test
areas of the reagent strips are saturated. To similarly minimize contact
of test strips in the waste receptacle with the walls and bottom thereof,
the tray 20 is formed with rails 38, 39 and 40 which may be extensions of
rails 32 to 34, respectively, and which extend vertically along the left
hand side wall 41, horizontally along bottom wall 42, and vertically along
the right hand end wall 43 of receptacle 28.
The tray 20 is formed with a pair of spaced parallel elongated slots 44 and
45 which extend from the right hand end of the loading area 25 at the left
of platform 26 to the right of platform 27 adjacent waste receptacle 28.
Slots 44 and 45 extend through the platforms 26 and 27, and to minimize
any liquid flow from the tray bottom through said slots, the latter are
provided with raised lip portions at the margins thereof.
In the loading area 25 the tray 20 is formed adjacent the rail 29 with a
vertical surface portion which extends above the level of the upper
surfaces of rails 29 and 30. At its left hand end the surface 46 is spaced
from rail 29, and at its right hand end it merges with a vertical surface
47 which is generally parallel with rail 29 and is disposed closer thereto
than the left hand end of surface 46. Surface 46 is positioned for
engagement by the inner end portion of reagent test strips placed
transversely on rails 29 and 30 in the loading area for a purpose to be
described hereinafter.
The instrument is provided with a driving and guiding mechanism which will
now be described with reference to FIGS. 1, 3 and 4. A source of driving
power in the form of a stepper motor 48 is mounted on the back side of the
rear wall 13 of frame 11 and has a drive shaft 49 connected to a flexible
coupling 50 which, in turn, is connected to a coaxial shaft 51. Frame 11
is provided with a supporting bearing 52 for shaft 51 spaced from the
frame wall 12, as well as with a supporting bearing in wall 12 in which
the shaft 51 is rotatably mounted and through which it projects.
Frame 11 is also provided with a supporting bearing 53 spaced from and
corresponding to the bearing 52, as well as with a coaxial bearing in the
frame wall 12. A shaft 54 is rotatably mounted in and extends through the
latter bearing, as well as the bearing 53. The shafts 51 and 54 are
parallel and respectively have coaxially fixed thereon between the wall 12
and bearings 52 and 53, like timing pulleys 51a and 54a which are
drivingly connected by a timing belt 56. Shafts 51 and 54 are thereby
driven at the same speed and in the same direction during operation of the
motor 48.
The shafts 51 and 54 have fixed coaxially on the front ends thereof
identical wheels 57 and 58 which respectively carry radially offset shafts
59 and 60 on which are mounted actuating members in the form of
cylindrical ball bearings 61 and 62 (FIG. 4) respectively, held in place
by nuts 63 and 64. The timing of the shafts 51 and 54 is such that the
offset shafts 59 and 60 are always at the same angularity during rotation
of shafts 51 and 54. For example, when offset shaft 59 is at the apex of
its circular travel, shaft 60 is also at the apex of its circular travel.
A vertically disposed generally rectangular plate 65 is formed with
shoulder means in the form of a pair of spaced parallel oblong slots 66
and 67 in which the bearings 61 and 62 are slidably positioned,
respectively. The slots 66 and 67 have substantially the same width as the
outer diameter of the bearings 61 and 62, and in the illustrated
embodiment, said slots are angled about 45.degree. to the right of
vertical Near its lower edge the plate 65 carries on its inner surface a
pair of rearwardly projecting spaced parallel shafts 68 and 69 on which
are mounted shoulder means in the form of freely rotatable similar wheels
70 and 71, respectively, shown in FIG. 1.
Projecting forwardly from the front wall 12 of frame 11 are a pair of
similar rectangular bosses or shoulder members 72 and 73 having coplanar
horizontal lower surfaces 74 and 75, respectively, with which the wheels
70 and 71 coact. The plate 65 is provided with projections 76 and 77 at
opposite ends along the lower edge thereof and to which rearwardly
projecting eye bolts 78 and 79 are affixed. Corresponding forwardly
projecting eye bolts 80 and 81 are affixed to the front wall 12 of frame
11 above the eye bolts 78 and 79, respectively. Opposite ends of a helical
tension spring 82 are connected to eye bolts 78 and 80, and opposite ends
of a similar spring 83 are connected to eye bolts 79 and 81. The tension
of springs 82 and 83 continually exerts an upward force on the plate 65
tending to bias the wheels 70 and 71 into contact with the shoulder
surfaces 74 and 75, respectively.
In FIGS. 1 and 4 the bearings 61 and 62 are located at the lower ends of
slots 66 and 67, and the plate 65 is in raised position and is generally
as far to the right as it can go. This is the reading or dwell position
which will be referred to hereinafter. Upon rotation of the shafts 51 and
54 in a clockwise direction, the bearings 61 and 62 travel in a clockwise
circular path and impart the same movement to plate 65, moving the wheels
70 and 71 out of contact with the shoulder surfaces 74 and 75 against the
bias of springs 82 and 83 during such movement. As the plate 65 and wheels
70 and 71 travel downwardly and thence upwardly toward the left along the
aforementioned clockwise circular path, the wheels 70 and 71 are returned
to contact with the shoulder surfaces 74 and 75 under the bias of springs
82 and 83, thereby terminating the circular path movement thereof.
Upon contact of wheels 70 and 71 with shoulder surfaces 74 and 75, plate 65
is again in raised position and is generally as far to the left as it can
go. During contact of wheels 70 and 71 with surfaces 74 and 75, the plate
65 can not continue to follow the circular path of the bearings 61 and 62.
As a result, on continued clockwise rotation of the shafts 51 and 54, the
bearings 61 and 62 slide to the upper ends of slots 66 and 67 as they
approach their apex position, and only the horizontal component of their
circular movement is imparted to the plate 65, moving the latter
rectilinearly to the right along a path parallel with surfaces 74 and 75.
As bearings 61 and 62 continue their circular travel beyond their apex
position, they then slide to the lower end of slots 66 and 67 as the
horizontal component of their movement continues the rectilinear movement
of plate 65, returning the latter to the position thereof in FIG. 1.
It will be apparent that one revolution of shafts 51 and 54 causes the
plate 65 to traverse an orbital path in a vertical plane, which path
comprises a rectilinear horizontal extent and a circular extent. The
orbital path of plate 65, as traced by the axes of the wheels 70 and 71,
is shown in FIG. 1 by the dot and dash lines 70a and 71a.
As part of the control system for the instrument, the plate 65 carries at
its right hand edge, as viewed in FIGS. 1 and 3, a switch actuating
element 153 for coaction with a switch 154 mounted on the front wall 12 of
frame 11. The switch 154 and element 153 can be of any suitable type which
will provide actuation of the switch 154, i.e. completion or interruption
of a circuit therethrough, by disposition of the plate 65 in the dwell or
reading position thereof shown in FIG. 1.
Guiding means is provided to maintain the vertical alignment of the plate
65 during its orbital movement. Referring to FIGS. 1 and 6, the front wall
of frame 11 has a boss 84 projecting outwardly therefrom below plate 65.
Boss 84 extends outwardly beyond plate 65 as shown in FIG. 6, and a
vertical plate 85 is fixed at its lower edge, as by screws 85a, to the
boss 84. Coaxial set screws 86 and 87 are threaded into suitable bores in
wall 12 and plate 85, respectively, and have reduced diameter flat end
surface portions which have relatively close fitting sliding engagement
with the rear and front surface portions of plate 65 near the lower edge
of the latter.
Referring to FIGS. 3 and 7, an elongated vertical rib or boss 88 is formed
on the rear wall 13 of frame 11 and is bored at its upper end to receive
one end of a horizontal shaft 89, the other end of which is fixed in a
suitable bore in end wall 14 of frame 11. A shuttle block 90 is slidably
mounted on shaft 89, and depending from the front portion thereof near its
right hand end as viewed in FIGS. 1 and 3 is a vertical plate portion 91.
Block 90 and its plate portion 91 are formed along the front face thereof
with a pair of spaced parallel vertical ribs 92 and 93 which define the
margins of an elongated rectangular vertical groove 94.
A crank arm 95 is fixed on the inner end of shaft 54 and carries at its end
a cylindrical ball type bearing 96 which has a close fitting slidable fit
within groove 94. It will be apparent that, upon one complete rotation of
shaft 54, the crank arm will cause one complete reciprocation of the
shuttle block 90 along shaft 89 from its position shown in FIGS. 1 and 3
to a position adjacent boss 88 and back to its initial position shown.
Guiding means is provided for preventing any rotational movement of shuttle
block 90 during its reciprocating movement. To this end, as best shown in
FIG. 7, the rear wall 13 of frame 11 is formed along its lower edge with a
forwardly projecting boss 97 to the under side of which is fixed one end
of a horizontal bar 98 having parallel planar front and rear vertical
surfaces 99 and 100. The opposite end of the bar 98 is fixed to the lower
end of the vertical boss 88. The plate portion 91 which depends from the
shuttle block 90 is spaced adjacent the front surface 99 of bar 98, and a
bar portion 101 depends from shuttle block 90 and has its lower end spaced
adjacent the rear surface 100 of bar 98. A set screw 102 is threaded into
a suitable bore in the lower end of the plate portion 91 and has a reduced
diameter flat end surface in relatively close fitting sliding engagement
with the front surface 99 of bar 98. A set screw 103 is threaded into a
suitable bore in the lower end of bar portion 101 and has a reduced
diameter flat end surface which is in relatively close fitting sliding
engagement with the rear surface 100 of bar 98. It is apparent that the
coaction of the set screws 102 and 103 with the bar 98 prevents rotational
movement of the shuttle block 90 during reciprocation thereof.
Projecting upwardly from the left hand end of the shuttle block 90, as
viewed in FIGS. 1 and 3, is a vertical arm 104 which carries at its upper
end a forwardly projecting horizontal arm 105 which is parallel with the
frame wall 14 and bar 16. Arm 105 carries a pair of spaced upstanding
locating and retaining pegs 106 and 107 on its upper surface and provides
a support for a blotter member 108. Blotter 108 is generally L-shaped in
transverse cross section and has a horizontal extent which overlays the
bar 105 and is apertured to receive the locating and retaining pegs 106
and 107. The blotter 108 is formed of solid material, for example
organoplastic, and has a depending vertical rectangular plate portion 109
with a generally planar surface 110 formed with a multiplicity of parallel
vertical capillary size grooves. Along its lower edge the blotter 108 is
notched, as at 155 (FIG. 4) to accomodate the rib 31, and it is also
notched as at 156 (FIG. 4) and 157 for a purpose which will appear
hereinafter.
Referring to FIGS. 1, 3, 4, and 6, a rectangular horizontal plate 111 is
secured, as by screws 112 and 113, to the upper edge of the rectangular
vertical plate 65, the plate 111 being recessed to accomodate the heads of
said screws below the upper surface of said plate. Adjacent its upper
surface, the right and left hand edges of the plate 111 are formed with
flanges 114 and 115 which extend from front to rear and provide extensions
of said upper surface.
As best shown in FIG. 5, a reagent strip advancing member 116 preferably
takes the form of a generally rectangular tray which has a downwardly
offset portion 117 at the left hand end thereof and is provided along its
edges with a continuous upstanding lip for retention of any liquid which
may collect thereon. The strip advancing member 116 is formed on its
underside with transversely extending depending parallel brackets 118 and
119 (see FIGS. 1 and 8) which are generally L-shaped in cross section to
provide inturned flanges. The brackets 118 and 119 provide guideways for
the transverse slidable mounting of member 116 on horizontal plate 111
with the inturned flanges of said brackets engaged beneath the flanges 114
and 115 of plate 111 as shown in FIG. 1. The tray 116 is formed on its
underside adjacent its front edge with downwardly projecting stop members
158 and 158a (see FIGS. 5 and 8), which engage the front edge of the
horizontal plate 111 to define the operative position of said tray on the
plate.
The strip advancing member 116 is formed with a pair of spaced parallel
upstanding longitudinally extending ribs 120 and 121 which extend from the
offset portion 117 to a bit beyond the right hand end of member 116. The
upper edges of the ribs 120 and 121 are horizontal and coplanar, and
formed thereon are a plurality of equally spaced upstanding test strip
engaging fingers or pegs 122 and 123. In the illustrated embodiment there
are eleven pegs 122 and eleven pegs 123. The pegs 122 are transversely
aligned with the pegs 123, the pegs in each row being spaced apart a
distance sufficient to accommodate a test strip therebetween. The pegs 122
and 123 are advantageously of generally tear drop shape in horizontal
cross section to provide on their right hand side, as viewed in FIGS. 2
and 5, only point contact with a reagent strip moved thereby to thereby
minimize any adhesion therebetween which might occur due to surface
tension of the liquid specimens with which the test areas of the test
strips are saturated.
When the strip advancing member 116 is in operative position on the
horizontal plate 111, the ribs 120 and 121 thereof are aligned with the
slots 44 and 45, respectively, of base tray 20. The slots 44 and 45 are
wider than the ribs 120 and 121 and permit travel therethrough of the
latter and of the pegs carried thereby without contact with base tray 20.
During operation of the motor 48 the travel of vertical plate 65 along the
orbital path illustrated by the dot and dash lines 70a and 71a in FIG. 1
is also imparted to the strip advancing member 116, ribs 120 and 121 and
pegs 122 and 123. When the parts are in the position of FIG. 1, member 116
and pegs 122 and 123 are in their uppermost positions wherein said pegs
intersect and project above the plane of the upper edges of the rails 29
to 34.
As the motor 48 operates, element 153 (FIGS. 1 and 3) is moved away from
switch 154 and the member 116 and its pegs are moved downwardly, toward
the left, and then upwardly along the circular extent of the orbital path
to cause the pegs 122 and 123 to be withdrawn downardly through the slots
44 and 45 (FIGS. 1 and 2). When member 116 is in its lowermost position
along the circular extent of the orbital path, said pegs are spaced below
the bottom of base tray 20. As the member 116 reaches the end of the
circular extent of the orbital path, it is again in its uppermost position
and is as far to the left as it can go. It then moves to the right along
the horizontal rectilinear extent of the described orbital path, i.e.
parallel with the rails, and is returned to the position thereof shown in
FIG. 1, in which the element 153 is again in actuating position with
respect to switch 154. In the illustrated embodiment the member 116 and
its pegs travel horizontally toward the right 1.2065 cm (0.475 inches)
along the rectilinear extent of the orbital path.
In the illustrated embodiment of the invention the time required for the
motor to make one complete revolution, and thereby for the member 116 to
make one traverse of the orbital path thereof, is 3.8 seconds.
The color changes which the test areas of multiple reagent test strips
undergo are sensed, or read, in the instrument by reflectance photometry.
To this end a read head 124 (FIGS. 1 and 8 to 10) is suitably vertically
adjustably mounted, as by screws 159 and 160, on the right hand vertical
face of the support arm 18 in spaced relation above and in alignment with
the reading station platform 26. A similar read head 125 (FIG. 1) is
similarly vertically adjustably mounted on the right hand vertical face of
the support arm 19 in spaced relation above and in alignment with the
reading station platform 27. In FIG. 2 the read head 125 is removed to
better show the structure therebelow in the area of platform 27.
The read heads 124 and 125 in the illustrated embodiment provide the optics
for reflectance photometer reading of a test strip having up to ten
equally spaced test areas. Since multiple test strips ordinarily
incorporate reagent systems having significantly different incubation
times, i.e. the time periods after contact with the liquid specimen during
which a color change can develop responsive to the presence of a
particular specimen constituent and during which the developed color will
remain detectable, the optics of the read head 124 are positioned to read
those test areas of a strip which have a predetermined first incubation
time. Conversely, the optics of the read head 125 are positioned to read
those test areas of a strip which have a predetermined longer incubation
time, since a test strip will be read on platform 27 a predetermined time
after said strip is read on platform 26.
Referring to FIGS. 8 to 10 the read head 124 will be described, and it will
be understood that the read head 125 is of substantially the same
construction. The read head 124 is elongated and is generally L-shaped in
cross section as viewed from the front of the instrument, having a main
body portion 126 and a horizontally projecting toe portion 127. The upper
surface of the body portion 126 is recessed, as at 128, and a plurality of
spaced vertical grooves 129, for example six in number, are formed in the
bottom of the read head 124 as shown. The main body portion 126 is formed
with a plurality of equally spaced vertical through bores 130 which, in
the illustrated embodiment, are ten in number. The bores 130 are each
adapted to receive one end of a fiber optic element 131 which is held in
place by a set screw 132 as shown in FIG. 9. The other end of each element
131 communicates with light sensing means (not shown) in a known matter.
Alternatively, the other end of each element 131 can communicate with a
source of light (not shown) in a known manner.
The toe portion 127 is formed with a plurality of equally spaced angled
through bores 133, each of whose axes is coplanar with that of a
corresponding bore 130. The bores 133 are each adapted to receive one end
of a fiber optic element 134 which is held in place by a set screw 135 as
shown in FIG. 9. The other end of each element 134 communicates with a
source of light (not shown) in a known manner. Alternatively the other end
of each element 134 can communicate with light sensing means (not shown)
in a known manner. It will be observed that there are seven sets of optic
elements 131 and 134 in the illustrated embodiment.
Referring also to FIG. 2, a yoke member 136 has a horizontal portion 139
which is U-shaped in plan view and has apertured ear portions 137 and 138
at its opposite ends which normally overlay the upper surface of the read
head 124. The remainder of portion 139 normally overlays the upper surface
of supporting arm 18, as best shown in FIGS. 2 and 9. Yoke 136 also has a
vertical portion 140 which depends from the portion 139 in spaced relation
with the supporting arm 18, terminating at its lower edge in an apertured
inturned flange 141.
Removably secured to the flange 141, as by screws 142 and one or more
cooperable nut members 143, is strip engaging means comprising a plurality
of strip engaging or hold down members 144 having arcuate strip-engaging
surface portions adapted, when in operative position, to engage the
surface of platform 26 or the upper surface of a test strip disposed on
said platform. In the illustrated embodiment, the members 144 take the
form of wire leaf springs having arcuate free end portions. As shown in
FIG. 8, each of the strip engaging members 144 is aligned with the center
line of one of the grooves 129 in the bottom of read head 124.
As also shown in FIG. 8, when the strip engaging members 144 are in their
operative positions and engage a test strip disposed on the platform 26,
the engaged strip is pressed flat against the platform by said members.
This insures that the strip is retained in the proper spacial relationship
with the read head 124 while it is disposed on the platform 26.
The yoke 136 is secured to the read head 124 by means of screws 145 and 146
which extend through the apertures in ears 137 and 138, respectively, and
are threaded into receiving bores in the read head 124. As shown in
vertical section in FIG. 8, the screw 145 is threaded into a vertical
through bore 147 which is counterbored at its upper end, as at 148, to
accomodate a helical compression spring 149 which coaxially surrounds the
screw 145.
A similar counterbore and spring arrangement is associated with the screw
146. However, the lower end of screw 145 is provided with a cylindrical
tip portion 150 which projects from the bore 147 and is in position for
abutment with a vertical shoulder 151 on base tray 20 when the screw 145
is threaded into the operative position thereof shown in FIGS. 8 and 9. It
will be apparent that when screw 145 is in its operative position, the
base tray 20 cannot be removed because transverse forward movement thereof
is prevented by abutment of shoulder 151 with screw tip 150.
When the screws 145 and 146 are unscrewed, for example to the position of
screw 145 in FIG. 10, the compression springs surrounding said screws
expand axially to lift the yoke 136 and the members 144 to the positions
thereof illustrated in FIG. 10, wherein the strip engaging portions of
said members are disposed within the grooves 129 of the associated read
head. In this position the members 144 are spaced above the bottom of read
head 124, and the tip 150 of screw 145 is spaced above the shoulder 151,
to thereby permit removal of the tray 20 by forward movement thereof. The
arrangement just described provides an interlock which prevents removal of
tray 20 whenever the members 144 are in their operative positions shown in
FIGS. 8 and 9, in which positions they would be subject to damage by such
removal. The interlock thus permits removal of tray 20 only when the
members 144 are lifted to the protected retracted positions thereof shown
in FIG. 10.
Operation of the instrument will now be described. It will be assumed that
the instrument is empty of reagent test strips and that the motor 48 is
energized by the control circuit therefor (not shown) to cause clockwise
rotation of the shafts 51 and 54, and orbital movement of the strip
advancing member 116 as aforedescribed, as well as simultaneous horizontal
reciprocating movement of the blotter 108.
It will also be assumed that the reagent test strips to be read have ten
test areas thereon and that the reagents of seven of such areas have a
relatively short incubation time, whereas the reagents of the remaining
three test areas have a relatively longer incubation time. The fiber
optics for reading the seven test areas having the shorter incubation time
are mounted on read head 124 in positions for alignment with such areas,
and the fiber optics for reading the reagent test areas having the
relatively longer incubation time are mounted on the read head 125 in
positions for alignment with such areas.
During operation of motor 48, blotter 108 and the strip advancing member
116 with its pegs 122 and 123 move generally in opposite directions, i.e.
when the pegs 122 and 123 are in their raised positions and are moved to
the right (advancing) along the horizontal rectilinear extent of their
orbital path, the blotter 108 is simultaneously moved to the left
(retracting). As the blotter reaches its most retracted position, the pegs
122 and 123 reach their most advanced position, switch 154 is actuated,
and the motor 48 is stopped for a predetermined dwell period, as will be
described later herein.
During the aforementioned dwell period the operator places a liquid
specimen-saturated reagent test strip, such as the strip 152 (FIG. 2), on
the rails 29 and 30 in the loading area 25 of base tray 20 with the inner
end of said strip adjacent the angled vertical surface 46. For reasons
which will appear, wide variation in the placement of the strip can be
tolerated. Assume that the inner end of the strip is in contact with the
vertical surface 46 and that the strip is skewed at an angle of other than
90 degrees with respect to the rails 29 and 30. Advancing movement of the
blotter 108 caused by subsequent operation of motor 48 at the end of the
dwell period will then orient the strip into normality with the rails as
the blotter moves into contact with the left hand edge of the strip. As
the strip is thus oriented and contact with all of the test areas thereof
is made by the blotter 108, any excess specimen in such test areas is
removed by the blotter and drips into tray 20.
Simultaneously with the aforementioned orientation of a skewed test strip,
contact of the inner end of the strip with the angled vertical surface 46
causes endwise outward movement of the strip as it is advanced along the
rails by the blotter 108. The inner end of the strip ultimately moves to
and along vertical surface portion 47 which is parallel with the rails, to
thereby bring the test areas of the strip into transverse registration
with the respective sets of fiber optics in read head 124.
As the blotter 108 reaches its most advanced position, the strip advancing
member 116 completes its travel (clockwise as viewed in FIG. 1) along the
circular extent of its orbital path by lifting the pegs 122 and 123 to
their leftmost raised positions. The leftmost set of pegs 122 and 123 thus
arises behind the strip in contact with the blotter 108 when the latter is
in its most advanced position. Such disposition of the mentioned pegs
prevents the strip from following the blotter during subsequent retractile
movement of the latter. As the blotter 108 retracts, interference with
movement thereof by the leftmost pegs 122 and 123 is prevented by the
notches 156 and 157 (FIG. 4) in the lower edge of the blotter which
provide clearance for said pegs.
In the illustrated embodiment of the invention the control system for the
motor 48 continues operation thereof which causes simultaneous retractile
movement of the blotter 108 and horizontal advancing movement of the pegs
122 and 123 along the recilinear extent their orbital path toward their
most advanced position, a distance which, in the illustrated embodiment is
1.2065 cm (0.475 inches). Such rectilinear movement of the pegs 122 and
123 moves the reagent test strip contacted by the leftmost set thereof to
the right along the rails the same distance, while at the same time
positively maintaining the orientation of the strip in normality with the
rails. When the pegs reach the limit of their rectilinear advancing
movement, the blotter is about at the limit of its retractile movement,
the element 153 actuates the switch 154, and the control system stops
motor operation for a dwell period during which the operator can place the
next succeeding strip on the rails in the loading area. At the end of the
dwell period, the control system resumes operation of the motor, causing
the pegs 122 and 123 to travel along the circular extent of their orbital
path as the blotter 108 again advances. During such travel, the leftmost
set of pegs 122 and 123 is withdrawn downwardly out of contact with the
strip to below the tray 20 and is then moved to the left and upwardly to a
raised position wherein it is disposed behind the next succeeding strip
advanced by the blotter 108 as the latter moved to its most advanced
position. Counting from the left, the first mentioned strip is now
disposed between the second and third set of pegs 122 and 123, whereas the
next succeeding strip is disposed between the first and second set
thereof.
In the illustrated embodiment one complete cycle of movement of the pegs
122 and 123 along their orbital path takes 3.8 seconds. Since the strips
are at rest on the rails during movement of the pegs along the circular
extent of their orbital path, which movement takes about 1.9 seconds, the
total dwell time for the strips on the rails is the motor stoppage time of
6.2 seconds plus 1.9 seconds, or about 8.1 seconds. Each time that the
blotter 108 moves to its retracted position, which takes place about every
10 seconds, the operator places another test strip on the rails in the
loading area 25 of tray 20.
During the next interval of motor operation the first mentioned strip is
moved by the aforementioned second set of pegs 122 and 123 under the strip
engaging members 144 to reading position on the reading station platform
26 wherein, as shown in FIG. 8, the members 144 engage portions of the
strip between the test areas thereof and press the strip flat against the
platform 26. The pressing action of the members 144 insures that a
constant and predetermined precise vertical spacing exists between the
test areas of a strip on the platform 26 and the read head 124. The
mounting for the read heads is adjustable, and the position of each read
head is normally set when the instrument is assembled.
The first mentioned strip and each succeeding strip rests on the platform
26 for the total dwell time of about 8.1 seconds. During this period of
the test areas of the strip are read and the amount of each specimen
constituent causing a color change in a test area whose reagents have the
relatively short incubation time is sensed by reflectance photometry and
is preferably printed out by suitable print out means (not shown).
During each interval of motor operation the first mentioned strip and each
succeeding strip is moved along the rails 1.2065 cm (0.475 inches), after
which the strips are at rest during the aforementioned total dwell period
of about 8.1 seconds. By each interval of movement the strips are disposed
between successively advanced pairs of the pegs 122 and 123. The number of
the pegs 122 and 123, and the position of the second reading station
platform 27 and its associated read head 125 are selected so that the time
required for a strip to reach the platform 27 corresponds to the
relatively longer incubation time of the test areas of the strips to be
read at the platform 27.
One skilled in the art will recognize that to accommodate different
incubation times, the mounting for read head 27 can permit adjustment of
the position thereof along the rails and that a strip advancing member 116
with a different number of pegs 122 and 123, as well as a base tray 20
having an appropriately positioned platform 27, can be substituted for
those illustrated.
When the first mentioned strip reaches reading position on platform 27,
which position corresponds to the reading position thereof on platform 26
illustrated in FIG. 8, the test areas of said strip having the longer
incubation time are read during the dwell period. The amount of each
specimen constituent causing a color change in each such test area is
sensed by reflectance photometry and is also preferably printed out by the
aforementioned print out means.
After a test strip is read at the platform 27, further motor operation
causes the pegs 122 and 123 to advance the strip along the rails to the
waste receptacle 28. In the illustrated embodiment the receptacle 28 can
accommodate about 200 strips. Removal of the strips from receptacle 28 is
facilitated by the presence of the rails 38 to 40 therein which minimize
the possibility of such strips adhering to the receptacle walls.
When the last test strip of a given run has been read on platform 26 and
continued motor operation advances said strip off platform 26 toward
platform 27, the optics of read head 124 detect the absence of a strip on
platform 26 during the next dwell period. The position of the motor when
stopped for the dwell period will be termed the zero position thereof. The
microprocessor in the control system for the motor 48 is programmed so
that when the absence of a strip on platform 26 during a dwell period is
detected, operation of the instrument is continued until all of the strips
have been read at the platform 27, and deposited in the receptacle, after
which the control system rotates the motor about 120.degree. beyond its
usual stopping or zero position.
In the illustrated embodiment, the microprocessor of the control system is
programmed so that if the read head 124 sees no strip on the platform 26
during any dwell period for a period of 80 seconds, the motor 48 is
thereupon rotated 120.degree. beyond its zero position and stopped. This
insures that operation of the instrument is continued for the period
necessary for reading of the last strip of the run at the platform 27,
followed by deposit of said strip in receptacle 28.
When the motor 48 is in the position 120.degree. beyond its zero position,
the strip advancing member 116 is in lowered position along the circular
extent of its orbital path. In this lowered position, the pegs 122 and 123
are spaced below the adjacent bottom portion of base tray 20, thereby
permitting relative transverse movement of the member 116 and tray 20
without interfering contact of any parts thereof Thus, the control system
program always stops the motor 48 at the end of a run in a standby
position which permits ready removal of the base tray 20 and member 116
for emptying and/or washing. It will be recalled, however, that the tray
20 cannot be removed until the yoke screws 145 and 146 on read head 124
and the corresponding screws on read head 125 are unscrewed sufficiently
to raise the strip engaging members 144 up into the grooves 129 and at the
same time to retract the screw tip 150 at each read head above the related
tray shoulder 151. As mentioned earlier herein, the interlock thus
afforded prevents damage to the strip engaging members 144 which might
otherwise occur during removal of tray 20.
The illustrated embodiment of the invention is programmed to read and print
out the test results for 360 test strips per hour placed sequentially on
the rails in the loading area at 10 second intervals. This is a
substantial improvement over the rate at which test strips can be read
with prior instrumentation. The instrument permits wide variability in
placement of the strips on the rails and automatically orients the strips
in precise reading position on the reading station platforms with the test
areas of the strips in registration with the respective read head optics.
During such orientation the strips are blotted, and any skewing out of
normality with respect to the rails is corrected, and at the same time any
endwise movement thereof necessary to align the test areas with the
respective read head optics is effected during movement thereof by blotter
108. Finally, when the strip reaches reading position overlaying a reading
station platform, it is pressed flat thereagainst by the strip engaging
members 144 for the dwell period, during which the raised disposition of
the pegs 122 and 123 prevents any skewing of the strip out of alignment
with the read head optics while the strip is being read.
The improved instrument is well adapted for reading of test strips whose
test areas incorporate reagents having different incubation times. The
fiber optic elements can be transferred from one read head to another as
necessary to provide reading of each test area at the proper time interval
following placement of the strip on the rails in the loading area 25.
Various changes and modifications may be made in the illustrated embodiment
without departing from the spirit of the invention, and all of such
changes are contemplated as may come within the scope of the appended
claims.
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